Sir Oliver Robbins KCMG CB (born 20 April 1975), is a senior British civil servant who served as the Prime Minister's Europe Adviser and the chief Brexit negotiator from 2017 to 2019, being appointed Permanent Under-Secretary at the Foreign Office in 2025. He is a controversial figure among Brexit supporters for his perceived pro-European stance. He previously served as the Permanent Secretary at the Department for Exiting the European Union from July 2016 to September 2017, and as the Prime Minister's Advisor on Europe and Global Issues from June 2016 to July 2016. Between 2019 and 2025, he was an investment advisor with Goldman Sachs.

Prior to his roles relating to the European Union in HM Civil Service, Robbins served as Principal Private Secretary to the Prime Minister and Second Permanent Secretary at the Home Office.

Born in 1975 at Lambeth to Derek Robbins and Diana née Phillips, his father is Emeritus Professor of International Social Theory at the University of East London, where he has taught since it was founded as North East London Polytechnic in 1970, devoting his career to French post-structuralist social theory and the work of Pierre Bourdieu. His mother was also a civil servant, who later left her job to raise her children.

Educated at Colfe's School, a private school in Lee, South East London, Robbins then went up to Hertford College, Oxford, where he read Philosophy, Politics and Economics (PPE), graduating with a Bachelor of Arts (BA) degree in 1996. At Oxford, he was elected President of the Oxford Reform Club, a group promoting a federal European Union. He has been nicknamed "Sir Humphrey" after the Yes Minister Permanent Secretary character Sir Humphrey Appleby.

Robbins joined HM Treasury in 1996 after graduation, serving as Head of Corporate and Private Finance from 2003 to 2006, and then briefly as Head of Defence, Diplomacy and Intelligence Finance.

Robbins was appointed as Principal Private Secretary to the Prime Minister at 10 Downing Street in 2006, replacing Ivan Rogers for the last part of Tony Blair's administration and the start of Gordon Brown's. When Brown re-set the Prime Minister's Office organisation to be more like its pre-1997 form, Robbins briefly served as its director before leaving Number 10 in 2007 to become the Director of Intelligence and Security — later, Director of Intelligence, Security and Resilience — in the Cabinet Office.

In 2010, David Cameron's incoming administration reorganised the UK national security apparatus, and Robbins's post was reformulated as the Deputy National Security Advisor responsible for intelligence, security and resilience. In this role, Robbins negotiated with The Guardian on how to curtail its reporting of material leaked by Edward Snowden relating to the operations of the CIA and GCHQ. The Guardian described Robbins as "steely but punctiliously polite".

In January 2014, Robbins was appointed Director-General (Civil Service) at the Cabinet Office. In September 2015, Robbins moved to the Home Office as Second Permanent Secretary alongside Sir Mark Sedwill. He had responsibility for immigration and free movement, as well as the borders, immigration and citizenship system. During this role, Robbins was ordered to leave a meeting of the Home Affairs Select Committee after he was deemed to have given "unsatisfactory" answers about the budget for Border Force and to instead provide answers outside the hearing later the same day, which he did not do.